1. Field of the Invention
The present invention relates to a recoil starter for use as an engine starter and more particularly to an improved method for introducing a cooling air for engine, the method applied to the recoil starter including therein a power storage spiral spring.
2. Description of the Related Art
In general, the recoil starter of this type adopts a system wherein a rope wound around a rotary reel is pulled out thereby starting the engine via a one way clutch mechanism and the rope is wound up by a rewinding force of the spiral spring. The recoil starters of power storage type have been proposed in the art. For instance, a recoil starter (see Japanese Utility Model Publication No. 17810/1995 comprises: a starter pulley having a ratchet wheel engageable with a ratchet claw of a crankshaft; a power storage spiral spring adapted to store a driving force which is exerted on the starter pulley for bringing the crankshaft into rotation; and a recoil drum designed to be rotated through a predetermined number of revolutions for permitting the power storage spiral spring to store a predetermined amount of power, the recoil starter arranged such that the rotation of the crankshaft is inhibited until a predetermined amount of power is stored by the spiral spring, the spiral spring is wound up through a predetermined number of revolutions after the establishment of meshing engagement between the ratchet claw of the crankshaft and the ratchet wheel of the starter pulley, and the spiral spring wound up through the predetermined number of revolutions automatically carries out the activation of an engine. Another recoil starter (see Japanese Patent Application No.2000-337487) comprises a starter case having a bearing disposed on an axis of a crankshaft in face-to-face relation therewith; apivotally movable starter shaft inserted in the bearing; a one way clutch mechanism including one end of the starter shaft that extends from the bearing toward a crankshaft side and a part belonging to an engine; and a starter case unitary with the starter case and having a bearing for supporting the other end of the starter shaft; a reel pivotally mounted to the starter shaft as interposed between the above two bearings; a rope wound around a groove of the reel; a recoil spiral spring anchored to the starter case and the reel at both ends thereof and biased in a direction to wind up the rope; and a power storage spiral spring anchored to the reel and the starter shaft at both ends thereof and operative to resiliently transmit a reel torque to the starter shaft when the rope is pulled out.
Unfortunately, however, the aforementioned power storage type recoil starters of the prior art have the following problems.
In a case where the above recoil starter of power storage type is applied to a recoil starter of a type which is adapted to introduce a cooling air for engine from a recoil starter side including the rope, reel, recoil spiral spring and the like, a complicated internal structure only permits a method to introduce the cooling air only from a peripheral side of the starter case and hence, an efficient cooling of the engine cannot be accomplished. In addition, the conventional power storage spiral springs have a relatively large size because they require as much damping force as to oppose a starting resistance of the engine. As a result, the conventional power storage spiral springs encounter difficulties in fabrication and handlings thereof.
The invention has been accomplished for the purpose of overcoming the drawbacks of the prior art and has an object to provide a recoil starter of a power storage type which is easily applied to the recoil starter of the type wherein the cooling air for engine is introduced from the recoil starter side, and which features a capability of efficiently cooling the engine, easy fabrication and handlings of the power storage spiral spring and an enhanced assemblability.
A recoil starter according to the invention comprises: a starter case unitary with a starter shaft disposed on an axis of a crankshaft in face-to-face relation therewith; a one way clutch mechanism comprising a cylinder cam pivotally fitted on the starter shaft, a cup-shaped pulley mounted on an engine side, and a ratchet mechanism mounted to the pulley and brought into or out of engagement with the cylinder cam; a reel pivotally mounted to the starter shaft; a rope wound around a groove of the reel; a recoil spiral spring anchored to the starter case and the reel at both ends thereof and biased in a direction to wind up the rope; and a power storage spiral spring accommodated in a cassette type spring case and operative to resiliently transmit a reel torque to the cylinder cam when the rope is pulled out, wherein air inlet ports for introducing a cooling air for engine are disposed at an outside surface and outer periphery of the starter case, a side surface of the reel and a side surface of the spring case for the power storage spiral spring.
Another recoil starter according to the invention comprises: a starter case unitary with a starter shaft disposed on an axis of a crankshaft in face-to-face relation therewith;
a one way clutch mechanism comprising a cylinder cam pivotally fitted on the starter shaft, and a ratchet mechanism in which a ratchet pivotally mounted to the cylinder cam is brought into or out of engagement with a cup-shaped pulley mounted on an engine side; a reel pivotally mounted to the starter shaft; a rope wound around a groove of the reel; a recoil spiral spring anchored to the starter case and the reel at both ends thereof and biased in a direction to wind up the rope; and a power storage spiral spring accommodated in a cassette type spring case and operative to resiliently transmit a reel torque to the cylinder cam when the rope is pulled out, wherein air inlet ports for introducing a cooling air to said starter are disposed at an outside surface and outer periphery of the starter case, a side surface of the reel and a side surface of the spring case for the power storage spiral spring.
The recoil starter is further characterized in that a substantially U-shaped notch provided at an outer end of the power storage spiral spring is designed to engage with a projection formed by inwardly projecting a portion of a circumference of the spring case; in that a projection formed at the spring case for the power storage spiral spring is inserted through the reel and fixed thereto by folding a distal end of the projection; in that a part of the cylinder cam pivotally fitted on the starter shaft is inserted in a central hole in a bottom of the cup-shaped pulley whereas the ratchet of the one way clutch mechanism mounted within the cup-shaped pulley is deployed by a centrifugal force thereby to disengage from the cylinder cam; and in that the starter shaft has a two stage structure including a greater diameter portion closer to the reel and a smaller diameter portion defining a distal end portion of the shaft whereas the cylinder cam is fitted on the starter shaft as covering the smaller diameter portion and a part of the greater diameter portion